Prostate cancer is the second most common form of cancer in American males. Genotoxic agents, such as ionizing radiation, ultraviolet light, and oxidizing compounds generated in normal cellular processes, can damage DNA and are a major cause of cancer. Cells respond to these insults by inducing gene expression and mobilizing proteins to induce DNA repair for cell survival or commit to programmed cell death (apoptosis). Deformed Epidermal Autoregulatory Factor-1 (DEAF-1) is a mammalian transcription factor found in an emerging class of proteins associated with chromatin regulation and human disease. DEAF-1 maps to the human chromosomal region 11p15.5, which is lost or mutated in breast, ovarian, lung, pediatric, and prostate tumors. Decreased DEAF-1 protein expression is associated with poor patient outcome in prostate and colon cancers. The absence of DEAF-1 expression in Deaf-1 null mice results in neural tube defects, alterations in cell proliferation and apoptosis, and death at birth. DEAF-1 interacts with proteins associated with apoptosis or cell survival (Ku70, p53 and HSP90), and DEAF-1 is increased and/or stabilized in the human prostate cancer cell line PC3 following exposure to genotoxic agents. We hypothesize that post-translational modifications of DEAF-1 will regulate its subcellular localization and interaction with protein partners which in turn will determine the balance between cell proliferation and apoptosis. The Specific Aims of this proposal are: 1) Determine the subcellular localization of DEAF-1 protein in stably transfected PC3 cells treated with genotoxic stressors: UV, hydroxyurea, or H2O2 and correlate the localization with phosphorylation status, and 2) Identify nuclear and cytoplasmic proteins interacting with DEAF-1 protein in stably transfected PC3 cells. These studies model genotoxic stresses that are naturally occurring in cells or are produced by chemotherapeutic agents used in treating cancer. Identification of DEAF-1 protein modifications and interacting proteins may give mechanistic insights into targets for the treatment of prostate and other cancers. PUBLIC HEALTH RELEVANCE: The research environment and objectives of this proposal are consistent with the goals of the NIH Academic Research Enhancement Award (AREA) R15. The proposed research will be conducted by investigators (J. Huggenvik and M. Collard) and students (both undergraduate and graduate students) at Southern Illinois University School of Medicine in Carbondale, Illinois. The research is based on the observation that DEAF-1, like the tumor suppressor p53, is induced by genotoxic stressors and interacts with proteins that are involved in DNA repair, protein stabilization, and apoptosis. Regulation of DEAF-1 and the interaction with its protein partners will help determine a cell's survival or death and control normal development and tumor formation.